1. Technical Field
Example embodiments relate to a semiconductor device. Other example embodiments relate to a lead frame and a semiconductor device having a lead frame, wherein a semiconductor chip is positioned on a die pad by selectively rotating the semiconductor chip at a certain angle, the connection angles and lengths of wires for connecting the semiconductor chip and inner leads to each other are set to be constant. A molding resin may be coated on the lead frame to form a mold, so that the mold may be prevented from being distorted or lifted out of the lead frame. Other example embodiments relate to methods of manufacturing a lead frame and a semiconductor device.
2. Discussion of the Related Art
In general, semiconductor chips may be fabricated on a wafer by sequentially or repeatedly performing a plurality of unit processes, e.g., deposition, diffusion, exposure, etching, ion implantation and/or cleaning. Thus, a plurality of semiconductor chips may be fabricated on a wafer. Semiconductor chips may be arranged on a wafer in such a manner may be manufactured as a plurality of semiconductor devices through a package process. A semiconductor device may be manufactured as follows. A semiconductor chip may be die-bonded on one surface of a die pad attached to a lead frame. The semiconductor chip may be wire-bonded to leads arranged in a radial shape around the die pad with gold wires. Subsequently, the semiconductor chip and bonded portions thereof may be molded with a synthetic resin.
Recently, the size of a semiconductor chip has become smaller. Connection contact points provided at the edge of the semiconductor chip may be individually connected to the ends of a plurality of inner leads provided around a die pad with gold wires.
A conventional lead frame will be described with reference to FIG. 1. In FIG. 1, reference numeral 1 may denote a die pad, reference numeral 2 may denote a lead, reference numeral 3 may denote a semiconductor chip, and reference numeral 5 may denote a gold wire for electrically connecting an electrode pad of the semiconductor chip 3 to each lead 2.
When the semiconductor chip 3 is mounted on the lead frame, the preform material may be first provided on a central portion of the die pad 1 of the lead frame, the semiconductor chip 3 may then be adhered to the die pad 1 by applying pressure to the semiconductor chip 3 from the upper side of the chip 3. Typically, the semiconductor chip 3 may be formed by cutting a semiconductor wafer. The semiconductor chip 3 may be generally formed in the shape of a square. The shape of the die pad 1 may be generally formed to have a square larger than the semiconductor chip 3.
As the size of the semiconductor chip becomes smaller, the size of the die pad may become smaller, and the diameter of each wire for electrically connecting the die pad and the inner leads may also become smaller. Because the die pad may be formed in the shape of square, when the die pad is connected (e.g., die-attached) to the inner leads using the wires, the die attachment may be performed only at 0 or 90 degrees with respect to the inner leads of which the ends are arranged in parallel with the four surfaces of the die pad.
Therefore, when connection contact points formed along the die pad, which is becoming smaller, are connected to the inner leads using the wires, the angle and length between the wires may be reduced. For this reason, an electrical short phenomenon may be caused by a current flowing between the wires. Such a phenomenon may be caused on a corner portion between the semiconductor chip and the die pad.
The conventional lead frame may include isolation frames extending in four directions from the die pad. When the lead frame is molded using a molding resin, the molding resin may be molded to surround or enclose the semiconductor chip and the isolation frames. Accordingly, the molding resin may come into surface contact with the isolation frames, so that a bonding force between the top and bottom of the molding resin may be increased.